Western blot analysis of extracts from Jurkat cells, untreated (-) or treated with pervanadate (1 mM; +), using Phospho-c-Cbl (Tyr700) (D16D7) Rabbit mAb (left). The phospho-specificity of the antibody was verified by preincubating the antibody with c-Cbl (Tyr700) phosphopeptide (center) or with c-Cbl (Tyr700) nonphosphopeptide prior to incubation with the membrane (right).

Western blot analysis of extracts from Jurkat cells, untreated (-) or treated with pervanadate (1 mM; +), using Phospho-c-Cbl (Tyr700) (D16D7) Rabbit mAb (left). The phospho-specificity of the antibody was verified by preincubating the antibody with c-Cbl (Tyr700) phosphopeptide (center) or with c-Cbl (Tyr700) nonphosphopeptide prior to incubation with the membrane (right).

Western blot analysis of extracts from Jurkat cells, untreated (-) or treated with pervanadate (1 mM; +), using Phospho-c-Cbl (Tyr700) (D16D7) Rabbit mAb (left). The phospho-specificity of the antibody was verified by preincubating the antibody with c-Cbl (Tyr700) phosphopeptide (center) or with c-Cbl (Tyr700) nonphosphopeptide prior to incubation with the membrane (right).

The Phospho-EGF Receptor Pathway Sampler Kit provides an economical means to evaluate the activation status of multiple members of the EGF receptor pathway, including phosphorylated EGF receptor, Stat5, c-Cbl, Shc, Gab1, PLCγ1, Akt and p44/42 MAPK. The kit includes enough primary and secondary antibodies to perform two western blot experiments.

The epidermal growth factor (EGF) receptor is a transmembrane tyrosine kinase that belongs to the HER/ErbB protein family. Ligand binding results in receptor dimerization, autophosphorylation, activation of downstream signaling, internalization, and lysosomal degradation (1,2). Phosphorylation of EGF receptor (EGFR) at Tyr845 in the kinase domain is implicated in stabilizing the activation loop, maintaining the active state enzyme, and providing a binding surface for substrate proteins (3,4). c-Src is involved in phosphorylation of EGFR at Tyr845 (5). The SH2 domain of PLCγ binds at phospho-Tyr992, resulting in activation of PLCγ-mediated downstream signaling (6). Phosphorylation of EGFR at Tyr1045 creates a major docking site for the adaptor protein c-Cbl, leading to receptor ubiquitination and degradation following EGFR activation (7,8). The GRB2 adaptor protein binds activated EGFR at phospho-Tyr1068 (9). A pair of phosphorylated EGFR residues (Tyr1148 and Tyr1173) provide a docking site for the Shc scaffold protein, with both sites involved in MAP kinase signaling activation (2). Phosphorylation of EGFR at specific serine and threonine residues attenuates EGFR kinase activity. EGFR carboxy-terminal residues Ser1046 and Ser1047 are phosphorylated by CaM kinase II; mutation of either of these serines results in upregulated EGFR tyrosine autophosphorylation (10).